Well Tool Latching System

ABSTRACT

A system for securing well tools, such as gas lift valves, into a latching profile within a wellbore. A gas lift valve is provided having a latching arrangement wherein an apertured back-up ring is used to provide stability for the locking lugs throughout the process of latching and unlatching the gas lift valve.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to devices and methods for securing awell tool within a tubular portion of a wellbore. In particular aspects,the invention relates to a latching arrangement for releasably securinga gas lift valve within a side pocket mandrel.

2. Description of the Related Art

Secure and reliable latching arrangements are important for releasablysecuring devices within wellbore arrangements. Gas lift valves are onesuch device that is used to assist the flow of hydrocarbons to thesurface in a wellbore. The gas lift valve transmits a gas, such as airwhich has been pumped down the annulus, into the flowbore of theproduction tubing to increase the flow of hydrocarbons through theproduction tubing and toward the surface of the well. Typically, a gaslift valve is inserted into a side pocket mandrel in a production stringusing a kickover tool, as is well known in the art. A latchingarrangement is needed to secure the gas lift valve within a latchingprofile in the side pocket mandrel. If the valve is not properly latchedinto place, it may not function properly. In addition, a latchingarrangement that malfunctions may cause the valve to become stuck in theside pocket mandrel so that it cannot be removed without significantdamage to the valve or the surrounding wellbore components.

Prior art latching arrangements for gas lift valves are shown in U.S.Pat. No. 4,265,306 issued to Stout and U.S. Pat. No. 4,554,972 issued toMerritt.

SUMMARY OF THE INVENTION

The invention provides a system for securing well tools, such as gaslift valves, into a latching profile within a wellbore. In a describedembodiment, a gas lift valve is provided having a latching arrangementwherein an apertured back-up ring is used to provide stability for thelocking lugs throughout the process of latching and unlatching the gaslift valve. In addition, the structure of the backup ring provides apositive retractive force for urging of the locking lugs radiallyinwardly during withdrawal of the gas lift valve. An axially facing wallof the aperture of the backup ring exerts a compressive force upon thelower axial side of the locking lug, causing a sliding contact between achamfered surface on the lug and a shoulder on the latching profile.This sliding contact moves the locking lug radially inwardly.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and further aspects of the invention will be readilyappreciated by those of ordinary skill in the art as the same becomesbetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings in whichlike reference characters designate like or similar elements throughoutthe several figures of the drawing and wherein:

FIG. 1 is a side, cross-sectional view of an exemplary side pocketmandrel and gas lift valve having an improved latching system, inaccordance with the present invention.

FIG. 2 is a side, cross-sectional view of the devices shown in FIG. 1,now with the gas lift valve being inserted into the side pocket mandrel.

FIG. 3 is a side, cross-sectional view of the devices shown in FIGS.1-2, now in a fully latched position.

FIG. 4 is a side, cross-sectional view of the devices shown in FIGS.1-3, now beginning to be withdrawn from the side pocket mandrel.

FIG. 5 is a side, cross-sectional view of the devices shown in FIGS.1-4, now further withdrawn from the side pocket mandrel.

FIG. 6 is a side, cross-sectional view of the devices shown in FIGS.1-5, now withdrawn from the side pocket mandrel.

FIG. 7 is an axial cross-sectional view of the gas lift valve 12 takenalong lines 7-7 in FIG. 1.

FIG. 8 is an isometric view of an exemplary back-up ring used in the gaslift valve shown apart from other components.

FIG. 9 is an axial cross-sectional view of the gas lift valve 12 takenalong lines 9-9 in FIG. 2.

FIG. 10 is an enlarged cross-sectional detail view depicting a lockinglug member and the back-up ring.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The general operation of gas lift valves and side pocket mandrels iswell known in the art and described in further detail in U.S. Pat. No.7,360,602 issued to Kritzler et al. and U.S. Pat. No. 7,228,897 issuedto Holt, Jr. et al. Each of these patents is owned by the assignee ofthe present application and each is hereby incorporated by reference inits entirety. As is known in the art, the side pocket mandrel 10 is apocket or recess which lies substantially parallel to and alongside ofthe central flowbore of a string of production tubing within a wellbore.

FIG. 1 illustrates an exemplary side pocket mandrel 10 and a gas liftvalve 12 that can be removably latched within the mandrel 10. The sidepocket mandrel 10 includes a housing 14 that defines a central axialbore 16. It is noted that, within the context of this discussion theterms “axial” and “axially” will refer to the direction defined by thelongitudinal axis of the axial bore 16, and which is illustrated by thearrows 79 in FIGS. 1 and 2 as well as arrows 82 in FIGS. 4-6. The bore16 of the side pocket mandrel 10 has an enlarged diameter latchingprofile 18. It is noted that the transition between the bore 16 and thelatching profile 18 presents sloped shoulders 20, 22. Fluid openings 24are disposed through the housing 14 proximate the lower end of the bore16 to permit a gas that is pumped down into the external annulus 26 toenter the bore 16.

In FIG. 1, the gas lift valve 12 is depicted in an initial run-inposition prior to being disposed into and latched within the bore 16.Those of skill in the art will understand that a kickover tool, of atype known in the art is used to dispose the gas lift valve 12 into thebore 16. For clarity, the kickover tool is not depicted in the drawings.

The gas lift valve 12 includes a latch head 28 that is threadedlyaffixed to a generally cylindrical expander shaft 30. The shaft 30features a primary shaft portion 32 which presents a substantiallyuniform diameter along its length and an enlarged diameter annularportion 34. The lower end of expander shaft 30 is affixed to a bottomsub 36. A latch housing 38 radially surrounds the expander shaft 30 andis secured to the expander shaft 30 by a frangible shear member, such asshear pin 40, which passes through both the shaft 30 and the latchhousing 38. A radially enlarged spring chamber 42 is defined between thelatch housing 38 and the primary shaft portion 32. An axiallycompressible spring 44 is disposed within the spring chamber 42.

A further enlarged lug chamber 46 is defined below the spring chamber 42between the shaft 30 and the latch housing 38. In a preferredembodiment, a number of openings (one shown) 48 are disposed through thelatch housing 38 within the lug chamber 46. A back-up ring 50 isdisposed within the lug chamber 46 immediately below the spring 44. Theback-up ring 50 contains apertures 52. In a presently preferredembodiment, there are three apertures 52, although there may be more orfewer than three, if desired. A locking lug 54 is disposed within eachof the apertures 52. It can be seen from FIG. 1 that, during initialrun-in to the side pocket mandrel 10, the locking lugs 54 (one show)also reside partially within the window 48 of the latch housing 38 andabut the radially enlarged portion 34 of the expander shaft 30.

The structure and operation of an exemplary back-up ring 50, apertures52 and locking lugs 54 are better understood with further reference toFIGS. 7-9. As depicted in FIG. 8, the ring 50 features a generallycylindrical ring body 56 with an inwardly directed flange 58 at oneaxial end. The apertures 52 are entirely defined within the ring body 56so is as to each present a pair of axially facing walls 60, 62 and apair of angularly facing walls 64, 66. In a currently preferredembodiment, the apertures 52 are generally rectangular in shape.

Each of the locking lugs 54 includes a central lug body 68 with asubstantially flat radially outward face 67 and chamfered edge portions69 (see FIG. 10). Each of the lugs 54 also has a pair of ears 70 whichextend radially outwardly from the body 68. The locking lugs 54 areshaped and sized to reside within the apertures 52 in a complimentaryfashion. The lug members 54 each have a curved radially inner surface 71which will abut the outer radial surfaces 34 or 32 of the expander shaft30, as FIGS. 7 and 9 show. The ears 70 of each locking lug 54 functionto prevent the locking lug 54 from being moved radially outwardlythrough the windows 48 of the latch housing 38. When the locking lug 54is disposed within the aperture 52, the axially facing walls 60, 62prevent the lug member 54, as depicted in FIG. 10. The axially facingwalls 60, 62 abut axial faces 72, 74, respectively of the lug member 54.As a result, the lug member 54 can move radially inwardly and outwardlywith respect to the backup ring 50 (as illustrated by the phantom linesof 54′ in FIG. 10 illustrating a radially outwardly extended position).However, the lug member 54 is prevented from appreciably rotating awayin any substantial manner from the axially facing wall 62, (in thedirection illustrated by arrow 76) by the presence of the axially facingwall 60. The lug member 54 is also prevented from appreciably rotatingaway from the wall 60 (in the direction indicated by arrow 78) in anysubstantial manner by the presence of wall 62. A substantial rotation ofthe lug member 54 with respect to the walls 60 or 62 would be an amountof rotation that would preclude the lug member 54 from operatingproperly to move radially inwardly or outwardly to selectively latch thegas lift valve 12 into the side pocket mandrel 10. In addition, theangularly facing walls 64, 66 prevent angular rotation of the lugmembers 54, as FIGS. 7 and 9 illustrate.

The operation to insert the gas lift valve 12 into the side pocketmandrel 10 and latch it within is illustrated by FIGS. 1-3 as well as 7and 9. Beginning with the configurations shown in FIGS. 1 and 7, adownward compression force (illustrated by arrow 79) is applied to thelatch head 28 and latch housing 38. This downward force 79 compressesthe spring 44 between the latch housing and the backup ring 50, as FIG.2 depicts. The latching lugs 54 are moved from the lower end of windows52, as illustrated in FIG. 1, to the upper end of the windows 52, asshown in FIG. 2. In addition, the downward force moves the lug members54 from abutting the diametrically expanded section 34 of the expandershaft 30 (as shown in FIGS. 1 and 7) to a position wherein the curvedfaces 71 of the lug members 54 abut the reduced diameter portion 32 ofthe shaft 30 (see FIGS. 2 and 9). This permits the lug members 54 to bemoved radially inwardly by sliding contact between a chamfered edge 69of the lug with a sloped shoulder 80 (see FIG. 2) within the bore 16 ofthe side pocket mandrel 10. Once the lug members 54 have been movedradially inwardly, the compression force gas lift valve 12 is moveddownwardly to the position depicted in FIG. 3 wherein the latching lugmembers 54 are located within the latching profile 18 of the gas liftmandrel 10. At this point the downward force 79 is removed. Thecompression spring 44 will move the backup ring 50 axially downwardlywith respect to the latch housing 38 and expander shaft 30. The innerradial surfaces 71 of the lug members 54 will once again be abutting theexpanded diameter portion 34 of the expander shaft 30. As a result, thelug members 54 will extend outwardly into the latching profile 18,thereby latching the gas lift valve 12 in place against inadvertentremoval during operation.

FIGS. 4-6 illustrate removal of the gas lift valve 12 from the sidepocket mandrel 10. When it is desired to remove the gas lift valve 12,an upward pulling force, or removal force) is applied to the latch head28 (illustrated by arrow 82). As is known, the removal force istypically applied to the latch head by a suitable pulling tool (notshown). It is noted that the removal force 82 must be sufficient toshear the shear member 40. The force 82 first moves the gas lift valve12 upwardly to the position shown in FIG. 4 wherein the upper chamferededge 69 of the locking lugs 54 comes into contact with the shoulder 20of the latching profile 18. However, the lugs 54 cannot be movedradially inwardly at this point due to their abutting relation with theexpanded diameter portion 34 of the expander shaft 30. The removal force82 then shears the shear pin 40, as shown in FIG. 5. When this occurs,the latching head 28 and expander shaft 30 are freed to move withrespect to the surrounding latch housing 38. The radially expandedportion 34 of the expander shaft 30 will engage the flange 58 of thebackup ring 50, thereby drawings it axially upwardly. The radiallyexpanded portion 34 of the expander shaft 30 is also moved above thelocking lugs 54, thereby allowing them to be moved radially inwardly tothe position shown in FIG. 5, due to sliding contact with the shoulder20. It is noted that the lower axially facing wall 60 of the backup ring50 will exert a positive compressive force against the lower axial face72 of the locking lugs 54. This compressive force will ensure that thereis sliding contact between the upper chamfered edge 69 of the lugs 54and the shoulder 20 of the bore 16. This sliding contact will move thelugs 54 radially inwardly. As the lugs 54 are moved inwardly, they areprevented from axial rotation with respect to the latch housing 38 bysliding contact with the axially facing walls 60, 62 of the backup ring50. At this point, the gas lift valve 12 is freed to be removedcompletely from the side pocket mandrel 10, as further depicted in FIG.6.

The foregoing description is directed to particular embodiments of thepresent invention for the purpose of illustration and explanation. Itwill be apparent, however, to one skilled in the art that manymodifications and changes to the embodiment set forth above are possiblewithout departing from the scope and the spirit of the invention.

1. A latching arrangement for releasably securing a well tool within abore in a wellbore, the latching arrangement comprising: an outer radialhousing defining a window therein; a locking lug that is at leastpartially disposed within the window and is moveable radially inwardlyand outwardly with respect to the housing to removably lock the welltool within the bore; and a backup ring disposed within the housing, thebackup ring having a ring body having an aperture disposed therein, theaperture presenting first and second axially facing walls; and thelocking lug being at least partially disposed within the aperture of thebackup ring and presenting first and second axial surfaces which adjointhe first and second walls of the backup ring, thereby precludingsubstantial rotation of the locking lug with respect to the backup ring.2. The latching arrangement of claim 1 wherein the well tool is a gaslift valve.
 3. The latching arrangement of claim 1 wherein the lockinglug comprises a lug body and an ear portion which extends radially fromthe body, the ear portion preventing the locking lug from being movedentirely radially outwardly through the window.
 4. The latchingarrangement of claim 1 wherein: the backup ring has three apertures; andthere are three locking lugs.
 5. The latching arrangement of claim 1further comprising a mechanism for moving the locking lug radiallyoutwardly with respect to the housing.
 6. The latching arrangement ofclaim 5 wherein the mechanism for moving the locking lug comprises agenerally cylindrical expander shaft disposed radially within the valvehousing, locking lug and backup ring, the expander shaft presents: afirst section having a first diameter; a second section having a seconddiameter that is larger than the first diameter; and wherein theexpander shaft is axially moveable with respect to the locking lug tocause the locking lug to move radially outwardly as the lug is movedradially outwardly as the locking lug contacts the second section of theexpander shaft.
 7. The latching arrangement of claim 6 wherein theexpander shaft is releasably secured to the outer radial housing by afrangible shear member.
 8. A gas lift valve for use in a side pocketmandrel within a wellbore, the side pocket mandrel having a bore, thegas lift valve comprising: a valve housing defining a window therein; alocking lug that is moveable radially inwardly and outwardly through thewindow with respect to the valve housing for removably locking the gaslift valve into a latching profile in the bore; a backup ring disposedwithin the valve housing, the backup ring comprising a ring body havingan aperture disposed therein, the aperture presenting first and secondaxially facing walls; and the locking lug being at least partiallydisposed within the aperture of the backup ring.
 9. The gas lift valveof claim 8 further comprising a generally cylindrical expander shaftdisposed radially within the valve housing, locking lug and backup ring,the expander shaft presents: a first section having a first diameter;and a second section having a second diameter that is larger than thefirst diameter.
 10. The gas lift valve of claim 8 wherein the lockinglug comprises a lug body and an ear portion which extends radially fromthe body, the ear portion preventing the locking lug from being movedentirely radially outwardly through the window.
 11. The gas lift valveof claim 9 wherein the expander shaft is releasably secured to the valvehousing by a frangible shear member.
 12. The gas lift valve of claim 9wherein the expander shaft is axially moveable with respect to thelocking lug to cause the locking lug to move radially outwardly as thelug is moved radially outwardly as the locking lug contacts the secondsection of the expander shaft.
 13. A method for releasably securing awell tool within a bore in a wellbore, the method comprising the stepsof: disposing the well tool within the bore proximate a latching profilein the bore, the well tool having a latch housing which defines a windowtherein; urging a locking lug radially outwardly through the window andinto the latching profile; and providing sliding contact between thelocking lug and at least two axially facing walls of a backup ring lyingradially within the latch housing to prevent substantial axial rotationof the locking lug with respect to the latch housing during radialoutward movement of the to locking lug.
 14. The method of claim 13further comprising the steps of: moving the locking lug radiallyinwardly with respect to the latch housing; and providing slidingcontact between the locking lug and at least two axially facing walls ofa backup ring lying radially within the latch housing to preventsubstantial axial rotation of the locking lug with respect to the latchhousing during radial outward movement of the locking lug.
 15. Themethod of claim 14 wherein the locking lug is moved radially inwardly bycompressive contact between the locking lug and the backup ring, whichcauses the locking lug to be moved inwardly by sliding contact against ashoulder within the bore.